The present invention relates to a cellular telephone system and, more particularly, to a cellular telephone system having some cells in which intermodulation (IM) interference occurs.
A cellular telephone system includes a plurality of base stations covering a plurality of zones, or cells, respectively. While radio frequencies are assigned to each base station so that no interference occurs, IM, or cochannel, interference cannot be completely eliminated. Furthermore, this situation would be aggravated by introducing a new system into an area covered by the existing system. Especially, when the two base stations of the new and existing systems, which use adjacent radio frequencies, are installed in the same cell, IM interference is likely to occur. If a portable, or mobile, telephone receives at least two radio frequencies adjacent to each other, IM interference may occur.